U.S. Pat. No. 4,474,717 describes a process of injecting a small portion of plastics without introducing inert gas (preloading) followed by sectional introduction of inert gas using frequencies from 4 to 100 cycles per second and a pressure of 300-1500 psi (2 to 10 MPa) into the continuous passing plastic material. The result is a multi-layered inside foamed structure. The present invention expands this method by applying injection technology used in the combustion engine technology and reaching a more intensive penetration by higher pressure (40 to 200 MPa), higher frequency (100 to 1000 hz) and more exact dosing by controlled width of the pulses, frequency of the pulses and regulation of pressure using this technology. Various designs of nozzle and channels utilizing hydro-mechanical principles can be achieved for metal, bulk materials and highly viscous melts.
EP161614 shows a device for the injection of certain amount of medium into a fluid stream. The adding of the additives happens by a charging pump which is activated by the flowing medium. Energetic mixing is not possible because of the small pressure difference,
U.S. Pat. No. 5,913,324 describes a device for adding additives into a liquid stream of high viscosity using a supply member standing transversely to the direction of flow. Dosing occurs in a side stream and independently of the main stream.
Devices for adding additives after a plasticizing unit are described in EP 0 432 336, WO89053226 (blowing in of air), U.S. Pat. No. 4,931,236 (spraying in of air/gas to obtain a hose with a foamed layer), and DEI 948454, BAYER, 1971 (injection of a chemical gas producer).
Use of a nozzle for the application of glue by pulsation is described in U.S. Pat. No. 5,934,521. As described, a nozzle-needle is activated by a pneumatic cylinder to move up and down, so that glue pours out in a pulsing way.
It has been known in burner systems, airless jet systems and spraying systems (atomizers) to add liquid or gas by pulsation. The present invention distinguishes from these applications by using a higher pressure of the liquid than 40 MPa and high energetic atomizing. This pressure is not possible with the nozzles used at this time. Only by electrical activated hydraulic servo valves in common rail technology can these pulsations be realized.